The present invention relates to an automatic moisture or ash analyzers and the like, and more particularly, to an apparatus and a method for loading crucibles containing samples and weighing them during such analysis in such a manner as to allow tests of different samples having different dwell times in the analyzer be performed simultaneously.
Systems for moisture or ash analysis of products such as food, coal, and cement through the use of heat are well known. The samples are placed in crucibles and the weight of the sample calculated from the weight of the empty crucible and the weight of the crucible and sample. The crucibles are in turn seated on a platter or carousel positioned within a furnace chamber. A weighing platform is positioned within the furnace chamber. The samples are subject to a heating and cooling cycle. The carousel then continuously deposits the crucibles in a predetermined sequence on the weighing platform and the weights of the crucibles monitored to analyze moisture or ash content based on weight loss during heating.
U.S. Pat. No. 4,522,788, to Sitek et al., issued on Jun. 11, 1985, is directed to such a system. In this patent, the furnace chamber is opened and a number of crucibles are manually placed on a carousel for the analysis. The crucibles are weighted empty using an internal balance, the samples are then added to the crucibles and weighted. The crucibles and samples are heated in nitrogen atmosphere to remove moisture, after moisture is obtained the furnace lid partially opens to install covers manually on top of crucibles, covers are weighed, furnace lid closes and heats up to obtain volatiles. The crucible samples and covers are cooled down to approximately 600° C., the furnace lid opens partially and covers are removed manually in the presence of nitrogen atmosphere. The lid closes and the furnace is heated in oxygen atmosphere to obtain ash. The furnace chamber is cooled down to room temperature then reopened and the crucibles removed.
There is a need for a moisture or ash analysis system that can automatically insert and remove crucibles in a furnace chamber at the appropriate stages of the analysis without requiring manual intervention, cooling of the furnace chamber or opening of the furnace chamber in order to make the analyses more efficient and safer. There is also a need for a moisture or ash analysis system which is capable of analyzing simultaneously different samples having different dwell times during the test.